1. Field of the Invention
The present invention relates to a printed circuit board for an optical waveguide and a method of manufacturing the same, and more particularly to a printed circuit board for an optical waveguide and a method of manufacturing the same, which is capable of being used to efficiently manufacture an optical waveguide using a relatively small amount of core material, compared to a conventional process, by locally applying core material only on the area of a lower clad layer, which is exposed through a through-hole of an insulation layer, and forming a core part through patterning.
2. Description of the Prior Art
These days, the demand for optical substrates, including various wirings, which enable electrical signals or optical signals to be transmitted to mobile devices or network devices requiring high-speed data transmission, is rapidly increasing.
Optical transmission wires, which are typically produced using polymer material having low light transmission, are each comprised of a core part, through which signals are transmitted and which has a square section having a thickness of 50 μm, and a clad part, enveloping the core part. The square sectional core part is typically manufactured using a photo-etching technique.
Referring to FIGS. 4A to 4C, a conventional method of manufacturing a printed circuit board for an optical waveguide will be described.
First, a flexible substrate is comprised of a copper layer 11 and a polyimide layer 12, and a lower clad layer 13 and a core layer 14 are sequentially formed on the polyimide layer 12 of the flexible substrate (see FIG. 4A).
Then, the core layer 14 is patterned through a typical photo-etching process, to thus form a core part 14a (see FIG. 4B).
Finally, an upper clad layer 15 is formed on the lower clad layer 13, on which the core part 14a is formed, thus providing a printed circuit board for an optical waveguide (see FIG. 4C).
According to the above-described conventional method, a core material is applied to the entire work surface of the substrate, to thus form the core layer 14, and the core material is patterned through light exposure and development, to thus form the core part 14a. Accordingly, the conventional method has a disadvantage in that a relatively large amount of core material is removed, compared to the amount required for formation of the core part 14a, thus increasing material costs. In particular, taking into consideration the high cost of optical wiring material, an economic and efficient method that is capable of being used to manufacture an optical substrate is desperately required.